The true identity of the Scarlet Pimpernel is threatened with exposure when a foppish young aristocrat is mistaken for Sir Percy.

When brilliant French scientist, Antoine Picard, is coerced into producing a revolutionary bomb for Citizen Robespierre, only the Scarlet Pimpernel, aided by Picard's beautiful sister Francoise, can rescue him from the guillotine.

More adventures with Sir Percy Blakeney and his crew as he uses ingenious disguises and tricks to rescue French aristocrats from the guillotine, and escape the cluthes of Robespierre. And a new challenge for Percy - Margueritte has died in childbirth leaving him with a baby daughter to look after.